1. Field of the Invention
The invention relates to a 1,3-dioxane derivative, particularly a 1,3-dioxane derivative which may be suitable for a liquid crystal compound, a liquid crystal composition and a display device; a composition and a display device containing the same.
2. Description of the Related Art
Liquid crystals (liquid crystal compounds) have been widely used in devices such as displays, optical elements such as retardation films and other applications, but the development of new materials suitable for these objects have been desired. Demands for liquid crystal materials include a reduction of a threshold voltage and an increase of a contrast.
A threshold voltage (Vth) is, as represented by the following formula, a function of dielectric anisotropy (Δε) (refer to Mol. Cryst. Liq. Cryst., 12, 57 (1970)).Vth=π{K/(ε0×|Δε|)}1/2
In the above formula, K represents an elastic constant, and ε0 represents a dielectric constant in vacuum.
As shown in the formula, a threshold voltage (Vth) is decreased by increasing the absolute value of a dielectric anisotropy (Δε), and/or decreasing an elastic constant K. Accordingly, liquid crystalline compounds having a large dielectric anisotropy (Δε) have been intensively developed.
Under such circumstance, for example, a 1,3-dioxane derivative is disclosed as a liquid crystal material having a positive dielectric anisotropy in U.S. Pat. No. 4,313,878. For display devices such as devices such as LCD, development of liquid crystal materials which are superior to conventional liquid crystals in intended optical performance and others have been further desired.